subsequent calls for f_vector fail if first attempt fails

src/sage/geometry/polyhedron/combinatorial_polyhedron/base.pyx

@@ -264,6 +264,20 @@ cdef class CombinatorialPolyhedron(SageObject):
         (A vertex at (0, 0),)
         sage: CombinatorialPolyhedron(3r)
         A 3-dimensional combinatorial polyhedron with 0 facets
+
+    Check that on wrong input subsequent calls of ``f_vector`` fail::
+
+        sage: data = P.incidence_matrix()
+        sage: vert = P.Vrepresentation()
+        sage: C = CombinatorialPolyhedron(data, Vrepr=vert)
+        sage: C.f_vector()
+        Traceback (most recent call last):
+        ...
+        ValueError: not all vertices are intersections of facets
+        sage: C.f_vector()
+        Traceback (most recent call last):
+        ...
+        ValueError: not all vertices are intersections of facets
     """
     def __init__(self, data, Vrepr=None, facets=None, unbounded=False, far_face=None):
         r"""
@@ -1458,21 +1472,23 @@ cdef class CombinatorialPolyhedron(SageObject):
 
         # Copy ``f_vector``.
         if dual:
+            if dim > 1 and f_vector[1] < self._n_facets:
+                # The input seemed to be wrong.
+                raise ValueError("not all facets are joins of vertices")
+
             # We have computed the ``f_vector`` of the dual.
             # Reverse it:
             self._f_vector = \
                 tuple(smallInteger(f_vector[dim+1-i]) for i in range(dim+2))
 
-            # The input seemed to be wrong.
-            if dim > 1 and self._f_vector[dim] < self._n_facets:
-                raise ValueError("not all facets are joins of vertices")
         else:
-            self._f_vector = tuple(smallInteger(f_vector[i]) for i in range(dim+2))
-
             if not self._unbounded and dim > 1 \
-                    and self._f_vector[1] < self._length_Vrepr - len(self.far_face_tuple):
+                    and f_vector[1] < self._length_Vrepr - len(self.far_face_tuple):
+                # The input seemed to be wrong.
                 raise ValueError("not all vertices are intersections of facets")
 
+            self._f_vector = tuple(smallInteger(f_vector[i]) for i in range(dim+2))
+
     cdef int _compute_edges(self, dual) except -1:
         r"""
         Compute the edges of the polyhedron.